Composition of matter



WILLIAM amen 21mm, or wiinmsmx;

sreummrs, rro DISPERSIONS rnocnss, me, or

Patented June 10, 1930 'TION OF DELAWARE '30 Drawing.

This invention relates to a coin" sition of matter comprising a' suspension rubber in bodies of the nature of oils, waxes; gums or bitumens in which the rubber is normally 5 'immiscible,'and also to a process of producing the same. I

It is known,'of course, that rubber (either crude or reclaimed rubber) may be dissolved in suchorganic solvents as benzol,

naphtha, gasolene and other so-called rubher solvents, and it .is also knownthat it is possible to stir crude or reclaimed rubber into or .mix it with such substances as engine oils petrolatum, rosin,'the so-called mineral rubbers and the like, to form what appearto be homogeneous mixtures when the are cold;

. but, so far as myknowledg'e goes, 1t has been considered im ossible to disperse crude or reclaimed rub er in a hot oil,'wax, gum or bitumen in such manner that wlien the mixture is cooled the rubber will remain uniformlv dispersed throughout the mixture, es cially if the mixture be again heated. or example, if a resin, wax, bitumen or oil or a mixture thereof is heated to a temperature pe of, $2. C. and it'be attem ted to dissolve the rubber therein, the ru ber in spite of mechanical agitation will finall separate and float as amass on the surface tli ereof and will not form a homogeneous mixturetherewith.. In fact, if the resin, oilorbitumen should be mixed with the rubberat a temperature at which would form a thick plastic mass and the rubber were kneaded thereinto, nevertheless, upon heating the mass to a temperature of about 120 (3., the rubber separates and rises to the top of the mass, thereby. preventlng a perfect mixture or dispersion.

It is also a recognized fact that rubber will depolymerize at a temperature of about 1 160 0., and as the temperature israised. the

rubber ultimately disintegrates, and, after a temperature is reached in which such disintegration is complete, the rubber can be frequently distilled from any higher-boilingpolnt oil with whichit is intermixed.

I have discovered that it is possible to efiect the dispersion of crude or reclaimed rubber in an oil, wax, gum, resin or bitumen or mixtures Application fled m 18,

HASACH'USETTS, ASSIGNOB, BY MEBNE AS- DOVER, DELAWARE, A CORPORA- conosrrron or naririm 1925. Serial No. 81,288.

thereof at any temperature from say, 100 C. to a temperature of; say, at which the depolymerization of the rubber would be h a previous application &e. g., Serial No. 662,556, filed Sept. 13, 1923) have described a method by which crude rubber may be dispersed in an a }ueous medium, by separatin the globules o rubber and su plying eac globule with a protective colloi a1 coating so that the resultant dispersion ma be diluted to any desirable-extent by the ad 'tion of water thereto, and so that by the elimination of the water therubber may be restored toa coagulated condition and vulcanized if de.-

sired.

I have further discovered ing and coating the globules of rub 'r with a.

protective colloidal coating, it is possible to isperse the rubber throng out a hot mass of substances with which the rubber is immiscible or which arenot socalled solvents of that, bgeseparat rubber, in such manner as to provide a stable, '7

physically-homogeneous suspension or -dis-' rslon. L .I have further discovered that by the addition of sulphur to such asuspension or dispersion, vulcanization of thedispersed rubber, but also to obtain manydifierent kinds of products. having difierent physical characteristics of viscosity, hardness, toughness, melting point lag, etc., and also to secure arr-efiective I control ofthese several'characteristics.

- In effecting the dispersion of the rubber in a non-solvent substance, the. o ration it is possible not only to efiect the may be performed in two steps. First, the

rubber isconditioned for dispersion by the employment of a suitable water-carrying colloidal dispersing agent; and, after the water has been removed, the rubber mass may by a second step be dispersed in the heated 011, wax, gum, resin .or bitumen or other nonsolveut at temperatures below 0., without causin t e depolymerization of'the rubber an a stable dispersion produced. While various colloidal dispersing or stabilizing agents mpg be utilized, such as/glue,

colloidal clay, a men orthe like, I prefer ordinarily to employ neutral casein. For ex- 4 ample, in preparing the rubber for disperslon in the organic non-solvents of rubber, one may proceed as follows :100 pounds of crude or reclaimed rubber are first milled on the usual compounding rolls in accordance with ordinary factory 'practiceto produce a workable rubber mass. There is now worked on incorporated into the plastic rubber mass,

globular spaces of the rubber mass and has ormed a protective film or coating about the globules of the rubber. On a compounding mill this ordinarily takes from 15 to 20 minutes, whereas in a two-blade mixer it may require from to 45 minutes. During the compounding or kneading process the heat generated thereby is ordinarily sufficient to cause the evaporation of a great portion of the water carried into the mass by the casein, although the rolls or the mixer may be heated .if desired. The mass may now be further heated sufficiently to dry out most of the water, although it is not necessary to remove the last traces of moisture as they are evaporated during the next step of the process.

The rubber casein mass, which comprises the rubber globules with their added protective coatings or films of colloidal casein, is now introduced into the non-solvent substance in which it is desired to disperse the rubber. ture of, say, 120 (1, about 60 pounds of resin, 20 pounds of Montan wax, 10 pounds of mineral rubber and 10 pounds of. copal gum until the components are molten, and I stir and agitate the mass so as to secure a substantially homogeneous mixture of the various components. The mass is not only physically homogeneous but is fairly viscous at the temperature stated, and when the mix ing operation has been completed, I now add the previously prepared rubber-casein mass and stir or knead it thoroughly into the previous mixture. During the stirring operation, the rubber mass slowly disintegrates substantially into its constituent globules (each protected by a colloidal coating) and uniformly disperses throu houtthe mass, and the rubber so dispersed is maintained in a uniformly dispersed condition throughout the mass regardless of an increase or diminu-.

tion in the temperature thereof, provided that the temperature is not raised materially above 160 C. or to a point which would cause a depolymerization of the rubber. The resulting product on being cooled has a melting point-which is practically the same Werner & Pfleiderer- For example, I heat to a tempera,

as the melting point of the mixture without the rubber, but it has-adhesive and cohesive properties greatly superior to or in excess of those of the mixture without the rubber.

It may again be heated to a molten condition without the separation of the rubber therefrom.

which I have referred to, or to the particular colloidal dispersing agent which I have described, to the proportions which I have indicated,-'or to the sequence of steps hereinb'efore stated. For example, the whole process may be-carried out in a steam-jacketed twoblade mixer of the Werner & Pfleiderer type, in which thecasein or other water-carrying colloid is worked and kneaded into the rubber, for after this has been accomplished there may be added to the mixer any suitable gums, resins, waxes or bitumens or combinations thereof into which the rubber is to be dispersed. In such case, it is desirable that the mixer shall be steam-jacketed, as stated,

so that it may be heated or chilled to the desired temperature for thepurpose of reduc ing the rubber non-solvents to a viscous workable mass.

It is possible, by selecting various rubber non-solvents in different proportions, to produce a normally solid or, viscous product having any desired melting point below 160 (3., since it seems to be the fact that the addition of the rubber to and its dispersion through the mass does not appreciably change the melting point thereof.

Another important feature of the present invention is the vulcanization of the dispersed rubber. This is accomplished by adding sulphur in the desirable quantity to the dispersion and heating the'mixture to a temperature at which the cure is edected,taking into account the necessary time element. After the dispersion of the colloidal protected rubber in the organic non-solvent (e. g., the mixture of rosin, Montan wax, mineral rubber and copal, referred to in the previous example) from 0.25% to 3.0% of sulphur, based on the weight of the rubber, is stirred into lit) the dispersion to form a homogeneous mixture, and the latter is heated from a tempera ture of, say, C. to 160 C. At these temperatures the rubber vulcanizes, the time required depending upon the temperature and to some extent upon the quantity of sulhur. With the roportions of sulphur herein stated the rubb ticity is not requisite, the proportionate quantity of sulphur may be increased to any desired amount.

' It seems to be the fact that a selectivity occurs, and that when only small quantities of sulphur are employed, there is a selective er is elastic, but when elas tion of the components of the non-solvent, the

action of the sulphur and the rubber, and even when the non-solvent comprises a gum, wax, bitumen or oil which is normally hard ened by or reacts with sulphur, the sulphur appears to react only with the dispersed rubber of the mass. When an excess of sulphur ponents of the non-solvent in which the rubber has been dispersed.

It further seems to be the fact that, by first effecting a homogeneous admixture of a colloidal dispersing agent throughout the rubber'mass so as to cause the separation of the rubber globules and their protection by en veloping colloidal films, it is possible to disperse the rubber globulesthroughout amass of rubber non-solvents such as oils, gums,

waxes, resins or bitumens, so as to produce a final product having any desirable adhesive.

and cohesive properties. For example, I have utilized such rubber-casein product as the basis of synthetic gutta-percha and balata, and have found use for such products in' the production of substances having almost identically the same characteristics as guttapercha, balata and chicle. By dispersing the colloidally protected rubber throughout a mass of any of the organic rubber nonsolvents which are suitable for the purpose, products similar to glue may be produced which are waterproof and which have adhesive' and cohesive properties much superior to those of glue, and whichcan be applied when the mass is rendered soft or plastic by heat, either by a spreading or a dipping operation. 7

Remarkable results are also achieved by curing the dispersed rubber with sulphur. In fact, according to the selection and proporpro ortion of the dispersed casein-protected rub er, and the quantity of sulphur employed, an accurate control is effected in producing many different products having any desired physical characteristics. For example, while.

the dispersion of the rubber in the non-solvent does not materially chan e the melting point of the non-solvent, by a ding various quantities of sulphur the melting point may be increased, and it is possible to control the lag, i. e., the temperature range between the soltening and the melting points of the mass.

' A thermoplastic mass produced by the dispersion of rubberin -a rubber non-solvent, either before or after the treatment with sulphur, may be itself dispersed in water by introducing a Water-carrying colloid into the-mass by a kneading operation, and then adding and kneading water thereinto until a change of phase occurs andthe water hecomes the continuous phase of the dispersion.

The thermoplastic mass, comprising colloidally protected rubber particles or globules dispersed throughout an organic non-solvent of rubber, such as oil's, waxes, bitumens, resins and the like, with or without sulphur, has'a wide application in the art. It may be used as an adhesive for saturating or treating fibrous materials, for waterproofing or a for insulating purposes, etc.

For the lack of a better comprehensive and generic term, I have employed in the appended claims the phrase non-aqueous substances which are non-solvents of rubber as referring to and including those substances water y the same process in which the rubber was initiallydisp ers'ed in Water.

By selection of suitable rubber non-solvents, the final product', in which the rubber is dispersed, may be normally adhesive when cold, ,or may be non-tacky when cold and highly adhesive when warmed.

A product-produced in accordance with the specific example herein given is tough or non-friable, rigid and stiff when cold, butis thermoplastic, and when heated may be either molded or may be spreadupon a fabric, or a fibrous material may be saturated therewith, or the product may be used as a glue or adhesive material. When sufiiciently warmed, it may bedrawn out into a continuous filament of a yard or more in length, and almost as fineas a spiders web. It has a tackiness and adhesiveness much greater than the mixture of gums and resins before the rubber is incorporated therein. While I prefer to employ crude rubber in most cases in producing my new composition of matter -comprising a substance, such as a gum, oil,=wax, resin or bitumen or a mixture or some of all of them, which is a non-solvent of non-polymerized rubber, and the colloidally coated rubber particles, yet in certain instances I employ reclaimed rubber or rubber substitutes so-callcd in lieu of crude rubber with excellent results.

Having thus explained the nature of my invention or discovery, the nature and certain properties-of the composition of matter and a process of producing the same, all however withput attempting to set forth all of the rubber, which comprises first incorporating a colloid in a rubber mass and then mixing the rubber-colloid mixture with and dispersing sufficient to depolymerize the rubber, and when the rubber has been dispersed mixingsulphur with the mass and effecting the vulcanization of the dispersed rubber.

3. A processof dispersing rubber in nonaqueous substances which are non-solvents of rubber, which comprises first plasticizing a rubber mass and coating its globules with an additional colloidal coating, and then intermixing the rubber mass with said non-solvent substance in liquid state until the rubber mass disintegrates and is dispersed unifermly throughout said substance as the disperse phase of the mass.

4. A process of dispersing rubber in nonaqueous substances which are non-solvents of rubber, which comprises first plasticizing a rubber mass and coating its globules with a colloidal coating, and then intermixing the rubber mass with said non-solvent substance in liquid state until the rubber mass disintegrates and is dispersed uniformly in colloidally-protected globules throughout said substance, and adding and stirring sulphur into the mass.

5. A process of dispersing rubber in nonaqueous substances which are non-solvents of rubber, which comprises first incorporating a water-carrying colloid and water in a rubber mass, and then mixing the resultant product in a molten mass of said non-solvent substance until the rubber is dispersed uniformly therein.

6. A process of dispersing rubber in nonaqueous substances which are non-solvents of rubber, which comprises first incorporatlng neutral casein and water in the rubber mass, and then mixing the resulting product with a liquid mass of said non-solvent substance, heated to a temperature below that which causes dopolymerization.

' 7. A process of dispersing rubber in nonaqueous substances which are non-solvents of rubber, which comprises first incorporating neutral casein and water in the rubber mass, mlxing the resulting product with a heated liquid mass of said non-solvent substance, and then vulcanizing the dispersed rubber.

8. A process'of dispersingrubber in nonaqueous substances which are non-solvents of rubber, which comprises first incorporating neutral casein and water in the rubber mass, removing the water, and mixing the rubbercasein product with and dispersing it in a heated liquid mass of said non-solvent substance.

9. A process of dispersing rubber in nonaqueous substances which are non-solvents of rubber, which comprises first incorporating neutral casein and water in the rubber mass, removing the water, and mixing the rubbercasein product with a heated mass of said non-solvent substance at a temperature rang ing from 120 C. to 160 C.

10. A process of dispersing rubber in nonaqueous substances which are non-solvents of rubber, which comprises first incorporating neutral casein and water in the rubber mass and dispersing the rubber in casein-protected particles in the water, removing the water, and mixing the rubber-casein product with a heated mass of said. non-solvent substance at a temperature ranging from 120 C. to 160 (3., and adding sulphur in sufiicient amount to vulcanize the dispersed rubber.

11. A composition of matter comprising a non-aqueous substance, which is a non-solvent of unvulcanized rubber, and rubber together with a colloidal agent uniformly dispersed therein, said non-aqueous substance constituting the continuous phase of the composition and amounting to greater than 20% by weight of the composition.

12. A composition of matter comprising a non-aqueous substance, which is a non-solvent of rubber, having dispersed therein colloidally-protected non-depolymerized rubber particles, said non-aqueous substance constituting the continuous phase of the composition and amounting to greater than 20% by weight of the composition.

13. A composition of matter comprising a non-aqueous substance, which is a non-solvent ot' rubber, having dispersed therein crude rubber globules, additionally coated with a colloid, and sulphur, said non-aqueous substance constituting the continuous phase of the composition and amounting to greater than 20% by weight of the composition.

14. A composition of matter comprising a non-aqueous substance, which is a non-solvent of rubber, crude rubber, and a colloid, the rubber globules being protected by the colloid and being non-separably dispersed and vulcanized in and throughout such substance, said non-aqueous su stance constituting the continuous phase of the composi-.

tion and amounting to greater than 20% by weight of the composition.

' 15. A composition of matter which is solid ing the continuous phase of the composition and amounting to greater than 20% by weight of the composition.

16. A'thermoplastic composition of matter comprisin minute rubber particles pro- -tected by a col oidal agent and dispersed in a thermoplatic body as the continuous phase and amounting to greater than 20% by weight of the com osition.

In testimony w ereof I have afiixed. my

signature. WILLIAM BEACH PRATT. 

